中国科学院过程工程研究所机构知识库

作为地球环境中的重要组成物质，氧气自出现以来就在生命演化的历程中扮演着关键的角色。以代谢过程是否需要氧气为标准，生命系统可以简单的分为耗氧和厌氧两大类。虽然氧气的出现根本性地改变了宏观有机生物体演化的方向，但是在多肽以及氨基酸的分子层次上，关于氧气对于这些多肽、蛋白类分子化学进化的调控却鲜有研究，而氧气如何影响和改变了这些生物内源分子的化学进化路径，并导致不同生物功能的组装体的形成仍然有待探索。受到自然界中含酪氨酸蛋白质有不同的氧化反应进化路径的启发，本课题分别以含酪氨酸的氨基酸衍生物、多肽以及酪蛋白为研究对象，通过控制氧气在反应体系中的含量来探究其对含酪氨酸分子的化学进化路径的影响，以及对生物功能的关键调控作用。通过改变含酪氨酸分子在反应体系中氧气的含量，我们分别获得了具有光热和光致发光现象的生物材料。所含有的酪氨酸基团会选择性地生成黑色素类似物或联二酪氨酸：在富氧条件下，酪氨酸基团向黑色素类似物转变的路径占有优势，得到的产物具有明显的光热效应；而在乏氧的环境中，酪氨酸基团将优先向联二酪氨酸转化，得到具有pH响应的发光材料。这种受氧气调控的化学进化现象，在含有酪氨酸的氨基酸衍生物、多肽以及蛋白质中均普遍存在，不同路径所得到的产物也都具有各不相同的组装结构。结合之前对于分子间弱相互作用（包括静电力、范德华力、π效应和疏水作用等）的协同组装形成有序结构的研究工作，提出了在此条件下导致不同组装结构形成的分子间相互作用机理。此外，进一步研究了联二酪氨酸在不同pH下的响应性发光行为。该项研究不仅揭示了氧气在含酪氨酸的生物内源分子化学进化中所发挥的调控作用，也为药物递送、光热治疗以及新型生物器件材料的设计提供了新的思路。;As a necessary component in the whole environment of our living planet, oxygen has played an important role in the evolution of life. Although the emergence of oxygen has fundamentally varied the evolution pathway of macro-organic organisms, there is little research on the regulation of oxygen on the chemical evolution of the peptides and proteins at the molecular level. It is still unclear how oxygen influences and changes the chemical evolution pathway of endogenous molecules and thus lead to materials with different assembled structures and biological functions. Inspired by the fact that tyrosine-containing proteins in nature have different evolution pathways of oxidation reactions, this thesis employs tyrosine-containing amino acid derivatives, peptides and casein to study the effects of oxygen on the chemical evolution pathway of tyrosine molecules and the key regulation of biological function. In this work, the vital role of oxygen has been demonstrated and these different materials with photothermal or luminescent effects have been obtained, respectively. These tyrosine residues tend to form dityrosine or melanin by controlling different oxygen concentrations. The pathway to melanin will be dominant when oxygen is rich. In the process, the product with photothermal effect can be obtained. However, the pathway to dityrosine will dictate the whole reaction when oxygen is really rare. And a kind of pH-responding material can be obtained eventually. This oxygen-controlled chemical evolution has ubiquitously been discovered from amino acid derivatives containing tyrosine residues to casein, a protein that contains many tyrosine residues. Besides, different pathways also lead to different self-assembly with distinctive structures. According to previous work involving the interactions between peptide molecules that lead to hierarchical structures, possible intermolecular interactions that dictate to the formation of different constructions have been proposed. Moreover, the photophysical behavior of dityrosine under different pH conditions also was studied. This work not only reveals the important role the oxygen is playing during the biomolecular evolution but also describes a blueprint in these area of drug delivery, photothermal therapy and novel bio-devices.